Blends of ABS and polycarbonate resins were disclosed in U.S. Pat. Nos. 3,130,177 and 3,852,393 and although found suitable for many end uses, their impact resistance presented a drawback for some important markets. Similar blends are disclosed in British Pat. No. 1,253,226 whereas U.S. Pat. No. 3,162,695 is noted for its teaching respecting a blend of polycarbonate and a graft copolymer of methylmethacrylate and styrene monomers polymerized in the presence of a butadiene styrene latex.
Further noted is U.S. Pat. No. 3,864,428 wherein taught are compositions comprising an aromatic polyester, a polycarbonate and a graft copolymer of butadiene. Acrylate based graft copolymers of the type entailed in the present invention are known. U.S. Pat. Nos. 3,808,180, 4,096,202 and 4,022,748 disclose acrylate based graft copolymers suitable in the present context yet none describe the present invention or suggest the presently disclosed advantages. Further noted is U.S. Pat. No. 3,761,440 which discloses that a compound corresponding to the present modifier serves in stabilizing pigmented polycarbonate compositions.
In accordance with Chem. Abstract 91:40371g, thermoplastic polyester compositions containing glass fiber reinforcement, poly(tetramethylene terephthalate) and a blend of diene rubber based polymer and glycidyl compound polymer, exhibiting an improved warping resistance have been disclosed in Jpn. Kokai Tokkyo Koho 79 23,565.
The efficacy of the presently claimed polymeric modifier in promoting the level of the mechanical properties of the blends of the present invention and in particular the impact strength of these blends have not at all been suggested - see for instance column 1, lines 67-71 of said U.S. Pat. No. 3,761,440, where the indication is that the notched impact strength of the pigmented polycarbonates, stabilized in accordance with that invention remains fully preserved.